Multilayer film for constructing skis

ABSTRACT

The invention concerns a multilayer film ( 15 ) for the construction of skis, a ski ( 1 ) having said multilayer film ( 15 ) and processes for the production of the multilayer film and the ski. The multilayer film ( 15 ) has a multilayer transfer or laminating film comprising two or more thin layers. A mechanically load-bearing layer with preferably a high modulus of elasticity is arranged on a surface of the multilayer transfer or laminating film. A cover layer is arranged on another surface of the multilayer transfer or laminating film. The multilayer film formed in that way is now applied to a base body of the ski ( 1 ).

The invention concerns a multilayer film for constructing skis, inparticular for application to a ski base body of an alpine ski, a waterski, a wakeboard, a kiteboard, a surfboard or a snowboard, a ski, inparticular an alpine ski or a snowboard, a process for the production ofa multilayer film for the construction of skis, and a process for theproduction of a ski.

In the production of skis, it has proven to be advantageous to apply tothe actual base body of the ski thin metal layers which on the one handas a structural component improve the skiing characteristics of the skiand on the other hand also afford visually attractive creative designoptions.

The invention is now based on a configuration of a ski, as is describedin WO 2/28491 A1.

In order to improve torsional resistance, the desired distribution ofweight and the desired flexural characteristic, it is proposed that athin metal layer is applied to the top side of the ski.

The ski comprises a base body which is formed from a piece of wood and aplurality of elements which are applied to that base body. The undersideof the base body has a thin metal layer and at the sides two steel edgeelements. Disposed beneath the metal layer is a sole or running surfacemade from a plastic material. Applied to the surface of the base body isa connecting layer which comprises a glass fiber cloth and which isglued by means of a resin to the metal layer disposed thereover and tothe base body. Graphic elements can then be applied to the metal layer.

The metal layers comprise steel, aluminum, aluminum alloys or titanium.The thickness of the metal layers is between 0.008 inch and 0.02 inch.

The procedure involved in production of the ski is as follows: the metallayer is glued by means of connecting strips to side portions. Theconnecting layer impregnated with resin is applied to the base body. Asalready described above the connecting layer provided in that way hasadhesive properties. Now the prefabricated element consisting of themetal layer, the side portions and the connecting strips is applied tothe connecting layer and pressure applied thereto by means of a mold sothat the prefabricated element is joined to the base body by theconnecting layer.

Now, the object of the invention is to improve the production of skis,in particular alpine skis and snowboards.

That object is attained by a multilayer film for the construction ofskis, having a multilayer transfer or laminating film comprising two ormore thin layers and on the one surface of which is arranged amechanically load-bearing layer with preferably a high modulus ofelasticity and on the other surface of which is arranged a cover layer.The invention further concerns a ski, in particular an alpine ski or asnowboard, in which such a multilayer film is applied to a ski basebody. The invention further concerns a process for the production of amultilayer film for the construction of skis, wherein a multilayertransfer or laminating film comprising two or more thin layers isapplied to a surface of a mechanically load-bearing layer with a highmodulus of elasticity and wherein a cover layer is applied to a surfaceof the multilayer transfer or laminating film, which is in oppositerelationship to the mechanically load-bearing layer. The inventionfurther concerns a process for the production of a ski, wherein amultilayer film as described hereinbefore is applied to a ski base body.

The term transfer or laminating film in accordance with the invention isused to denote the functional film body of a transfer or laminatingfilm, which does not include a backing or carrier film which is possiblyused for production of or for the application of such a transfer orlaminating film to an article (and which thereafter is usually removed,at least in the case of transfer films). The term ski in accordance withthe invention is used to denote all possible kinds of skis, for examplealpine skis, cross-country skis, snowboards, water skis, wakeboards,kiteboards or surfboards.

The invention affords the advantage that many different visual creativedesign options are afforded, while maintaining a high functionalstandard. The decoration process is simplified, and many differentdesign elements can be incorporated without a high level of complicationand expenditure. In addition the functional characteristics of the skisuch as for example the above-described parameters of torsionalresistance, desired distribution of weight and desired flexuralcharacteristic are promoted by the multilayer film according to theinvention.

A further advantage is that the production process for the production ofskis of a graphically attractive configuration is speeded up and reducedin cost.

A further advantage is that the graphic design elements of the ski aremaintained over a long period even with intensive use, which cannot beattained by the hitherto usual processes.

Advantageous configurations of the invention are set forth in theappendant claims.

It is desirable for the transfer or laminating film used to be in theform of a transfer film which has an adhesive layer, a functional layerand a release layer. The adhesive layer serve for glueing the filmstructure to the mechanically load-bearing layer. The release layer isadvantageously made up of a layer which permits good adhesive bonding tothe cover layer. Thus the release layer used can be a clear lacquerlayer which ensures excellent bonding, particularly when the cover layerused is a PMMA layer or PC layer (PMMA=polymethylmethacrylate,PC=polycarbonate) or also a layer of ABS or ABS blends.

The functional layer can be made up of one or more layers. Designoptions for the ski, which are particularly full of effect, can beafforded if one or more of the following layers is or are used as afunctional layer alone or in combination:

A metal layer, a thin film layer succession which produces color shiftsby means of interference, a replication layer into which diffractivestructures or macrostructures are embossed and which is combined with ametal layer and/or an HRI layer or an LRI layer (HRI=high refractionindex; LRI=low refraction index), or a color lacquer layer.

A color lacquer layer guarantees good visuals and shine. A meal layer incombination with a decoration print can serve as a further designelement. By means of a metal layer, it is possible to achieve a metalvisual look, in which respect further visually quite attractive elementsare achieved if a colored metal is used or if a colored lacquer layer isarranged in front of the metal layer.

The use of thin film layer successions makes it possible to producecolor shifts which are dependent on the viewing angle and which,depending on the respective viewing angle involved, can impart adifferent appearance to the ski. If a replication layer with diffractivestructures is used, then it is possible for example to use hologramrepresentations as further design elements.

It is advantageous if a thermoformable, in particular deep-drawable filmis used as the transfer or laminating film. In that way it is possiblefor the ski production process to be made still more efficient.

In order to guarantee the functional characteristics of the ski and tosatisfy the mechanical, chemical and climatic demands of a ski, it isadvantageous for the cover layer and the mechanically load-bearing layerto be shaped thicker than the transfer or laminating film, preferably ineach case at least 5× thicker than the transfer or laminating film.Advantageous thickness ranges for the cover layer are in a range ofbetween 50 and 125 μm. Advantageous thickness ranges for themechanically load-bearing layer are in the range of between 100 μm and 2mm.

Depending on the respective manner in which the multilayer film isjoined to the base body of the ski, it is advantageous for themechanically load-bearing layer or the cover layer to be of an embossedor structured nature. Such a configuration on the one hand promotes thefunctional properties and characteristics and on the other hand can alsoserve as an attractive optical creative design element.

It is further desirable for the mechanically load-bearing layer and/orthe cover layer to be transparent. In that respect it is in particularadvantageous for both layers to be transparent. The film can thus beused ‘double-sided’, which expands its area of use.

It has proven to be advantageous for the cover layer to be made fromthermoplastic material or from a screen printing ink or a castinglacquer. That guarantees good mechanical and chemical resistance. Inaddition that ensures good adhesion to the subjacent layers.

Further design options are afforded if additional decorations areprinted on the multilayer transfer or laminating film prior to theapplication of further layers.

Depending on the respectively desired functional characteristics themechanically load-bearing layer of the multilayer film or the coverlayer of the multilayer film can be joined to the ski base body. If thecover layer is joined to the ski base body, then in general the scratchresistance of the decorative elements is enhanced by virtue of thegenerally greater layer thickness of the mechanically load-bearinglayer.

The invention is described by way of example hereinafter by means of anumber of embodiments with reference to the accompanying drawings inwhich:

FIG. 1 is a view in section through a ski designed in accordance withthe invention,

FIG. 2 is a diagrammatic view of the structure of a multilayer filmaccording to the invention for a first embodiment,

FIG. 3 is a diagrammatic view of the structure of a multilayer filmaccording to the invention for a second embodiment,

FIG. 4 shows a diagrammatic view of a transfer film which is used in amultilayer film according to the invention, and

FIG. 5 shows a view in section through a multilayer film according tothe invention.

FIG. 1 shows an alpine ski 1. The ski has two edge elements 12, a soleor running surface element 11, a metal layer 13, a ski base body 14 anda multilayer film 15.

The running surface element 11 is made from a plastic material. The edgeelements 12 comprise steel. They are shaped in the usual form to performthe function of a steel edge of an alpine ski. The metal layer 13preferably comprises a high-strength steel, a high-strength aluminumalloy or titanium. The thickness of the metal layer 13 is preferablybetween 0.25 and 0.5 mm. The ski base body 14 comprises wood.

It is however also possible for the ski base body 14 to comprise anothermaterial, for example a plastic material. In addition it is possible forthe ski base body 14 to be made up of a plurality of layers. Itcomprises for example a wood core which is sheathed by a glass fibercloth. It is possible for that sheathing not to embrace the entiresurface of the wood core and thus to be an only partial enclosure.

It is further possible for the ski base body to be made up of a surfaceof thermoplastic material with a subjacent upper web of glass fibercloths or laminates, possibly in combination with a layer of Titanal.Those layers are applied either to a wood core or to a PU injectionmolded foam core.

The multilayer film 15 is so shaped that it covers the side surfaces ofthe ski base body 14 and the side of the ski base body 14, which is inopposite relationship to the sole running surface of the alpine ski 1.The multilayer film 15 is preferably of a thickness of between 0.25 and2 mm. It is also possible for the multilayer film 15 to be of a planarform and thus for example to be applied only to the side in oppositerelationship to the sole running surface or to the side surfaces of theski base body 14. It is further possible for the multilayer film 15 tocompletely enclose the ski base body 14.

The multilayer film 15 is preferably put into the appropriate shape bymeans of a thermoforming process and is then adhesively secured to theski base body 14. It is however also possible for the multilayer film 15to be pressed on to the ski base body 14 and, in that pressingoperation, the film 15 acquires the shape shown in FIG. 1 and at thesame time is glued to the ski base body 14.

The precise structure of the multilayer film 15 will now be described ingreater detail with reference to FIGS. 2 and 3 which each disclose thestructure of a film which can be used as the multilayer film 15.

FIG. 2 shows a multilayer film 2 which has a mechanically load-bearinglayer 24, a multilayer transfer or laminating film 23 comprising two ormore thin layers, and two cover layers 21 and 22.

The mechanically load-bearing layer 24 comprises a thermoplasticmaterial having a high modulus of elasticity. In this case the modulusof elasticity of the mechanically load-bearing layer 24 is preferably inthe range of between 800 and 2500 Mpa. The plastic materials used can bein particular styrene polymers such as for example ABS(ABS=acrylonitrile/butadiene/styrene), M-ABS+TPU (TPU=thermoplasticelastomers based on polyurethane), ABS+PC (PC=polycarbonate) as well aspolyurethanes such as in particular TPU. It is further possible to usePC plastic materials or PS plastic materials (PC=polycarbonate,PS=polystyrene). The thickness of the mechanically load-bearing layer ispreferably between 100 μm and 2 mm. In the preferred embodiment shown inFIG. 2 the thickness of the mechanically load-bearing layer 24 is 1.8mm.

The transfer or laminating film 23 comprises a VF chromium film(VF=vacuum formable). The thickness of the VF chromium film used isabout 5 μm. It comprises four layers. On the one hand, a release layerformed by a clear lacquer layer (polyacrylate) of about 2 μm inthickness. In addition, a functional layer which is formed by a layerabout 1 μm in thickness, comprising a lacquer suitable for vapordeposition and a thin, vapor-deposited chromium layer. Instead of achromium layer it is also possible to use other metal layers. Finally anadhesive layer of about 2 μm in thickness is applied.

In that respect it is possible for an additional UV protection (forexample cerium oxide, TiO₂, HALS and so forth) to be added to therelease layer and/or the layer of vapor-depositable lacquer.

The transfer film 23 can additionally be printed upon using screenprinting or additionally decorated using a thermotransfer process. It isfurther possible for the transfer film 23 to be printed upon by means ofan intaglio printing process or a flexoprinting process or another usualprinting process.

The cover layers 22 comprise a screen printing ink or a casting lacquer.In that respect preferably 2-component polyurethane inks are used as thescreen printing inks and casting lacquers. It is also possible for thecover layer 22 to comprise a layer of thermoplastic material, forexample PC plastic material (PC=polycarbonate), PMMA(polymethylmethacrylate) or ABS/TPU blends.

As shown in FIG. 2 it is also possible for two cover layers to beapplied to the transfer film 23. Thus for example the layer 22 can be acolored layer which under some circumstances is shaped in a patternconfiguration, comprising a screen printing ink or a casting lacquer.The layer 21 is a solution comprising a transparent casting lacquer, atransparent screen printing ink or a layer comprising a thermoplasticmaterial, for example PMMA.

The thickness of the overall cover layer is preferably between 50 and125 μm. In the embodiment illustrated in FIG. 2 the layer is of athickness of 50 μm and the layer 21 is of a thickness of 70 μm.

The cover layer can be not only smooth but also of a structured nature.Equally the mechanically load-bearing layer can be smooth or structured,for example embossed, brushed and/or scratched.

When the multilayer film 2 is applied to a ski base body, the outsidesurface of the multilayer film 2, which is formed by the mechanicallyload-bearing layer 24, is joined to the ski base body.

FIG. 3 shows the structure of a multilayer film 3 which can also beapplied as a multilayer film 15 to the ski base body 14.

The multilayer film 3 has a cover layer 33, a multilayer transfer orlaminating film 32 and a mechanically load-bearing layer 31. When themultilayer film 3 is applied to the ski base body 14 in this embodimentthe cover layer 33 is joined to the ski base body 14.

The mechanically load-bearing layer 31 is like the layer 24 shown inFIG. 2 and thus comprises a mechanically load-bearing thermoplasticlayer of a plastic material with a high modulus of elasticity. Thetransfer or laminating film 32 is like the transfer or laminating film23 shown in FIG. 2. The cover layer 33 involves a screen printing orcasting lacquer layer which is like the corresponding layer shown inFIG. 2. It is also possible for the layer 33 to comprise a layer ofprinting ink.

The above-illustrated layer structure makes it possible for theindividual layers of the multilayer film to be connected togetherwithout additional use of adhesive. The mechanically load-bearing layeris joined to the transfer film or laminating film by means of anextrusion process or a hot pressing or hot stamping process. In thatcase the mechanically load-bearing layer can be transparent or opaque.The cover layer is then applied, for example by means of a screenprinting process. It is also possible to use other processes, forexample dipping, spraying, flexoprinting, tampon printing, intaglioprinting, offset printing and so forth.

FIG. 4 now shows the structure of a transfer film which can be used forthe transfer or laminating films 23 and 32.

FIG. 4 shows a transfer film 4 and a carrier 41. In this case thecarrier 41 preferably comprises PET and is removed upon application ofthe transfer film 4 to the mechanically load-bearing layer of themultilayer film. The transfer film 4 has a release layer 42, areplication layer 43, two thin film layer successions 44 and 45, a metallayer 46 and an adhesive layer 47.

The release layer 42 serves to ensure that the transfer film 4 isreleased from the carrier 41 as well as possible. As already statedabove, it is advantageous in that respect to use for the release layer42 a material which ensures good adhesion of the cover layer of themultilayer film. That is achieved if a layer of polyacrylate is used asthe release layer 42. The preferred thickness of the release layer 42 isin the region of between 1 and 3 μm.

The release layer 42 thus performs a double function, on the one hand asa release layer in order to ensure release of the multilayer film 4 fromthe carrier 41 and secondly as a bonding layer for the cover layer ofthe multilayer film.

The replication layer 43 preferably comprises a replication lacquer or athermoplastic material. The thickness of the replication layer 43 is ofthe order of magnitude in the region of between 1 and 20 μm, preferablyin the region of between 5 μm and 12 μm. Polycarbonates or polyacrylatescan be used as thermoplastic materials for the replication layer 42.

One or more diffractive structures are embossed into the replicationlayer 43 by means of a transfer tool. Thus for example a hologram can beproduced by that diffractive structure by optical-diffraction effects.It is further possible for macrostructures or symmetrical-achromaticstructures or asymmetrical-achromatic structures such as for exampleblaze structures to be embossed. The application of a matt structure tothe replication layer 43 is also possible.

The thin film layers 44 and 45 form a thin film layer succession, bymeans of which color shifts which are dependent on the angle of view canbe produced. The layer 44 is an absorption layer formed for example by avery thin metal layer. The layer 45 is a spacer layer whose opticalthickness corresponds to the λ¼- or the λ 1/2-condition. The resultingoptical interference phenomena provide color shifts which are dependenton the angle of view, from the point of view of the viewer.

The absorption layer 43 is preferably applied by means of vacuumcoating, for example by means of PVD (PVD=physical vapor deposition) orsputtering. The thickness of the absorption layer 43 is betweenapproximately 30 and 150 Å. In this case the absorption layer is formedby a semi-opaque material, for example a chromium, nickel, titanium,vanadium, cobalt or palladium alloy. The semi-opaque material can alsobe formed by metal fluorides, metal oxides, metal sulfides or metalnitrides.

The spacer layer 44 comprises a transparent material. It can be in theform of a high-refraction layer (HRI=high refraction index) or alow-refraction layer (LRI=low refraction index). High-refractionmaterials which can be used are for example zinc sulfide (ZnS), zincoxide (ZnO), zirconium oxide (ZrO₂), magnesium oxide (MgO) or siliconnitride (Si₃N₄). Materials which can be used for a low-refraction layerare for example silicon oxide (SiO_(x)), aluminum oxide (Al₂O₃) andmetal fluorides such as for example magnesium fluoride (MgF₂).

It is also possible for the spacer layer 44 to be colored. It is furtherpossible, instead of the two thin film layers 44 and 45, to arrange athin film layer succession comprising a plurality of alternatelyarranged high-refraction and low-refraction thin film layers. It is alsopossible in that way to achieve color shifts which are dependent on theangle of view.

The metal layer 46 is formed for example by a chromium layer or analuminum layer.

The adhesive layer 47 can be formed by an acryl-based polymer or thelike.

Instead of using the transfer film 4 it is also possible to use alaminating film. In the case of such a laminating film the release layer42 is replaced by a bonding layer which is of a configuration forexample like the adhesive layer 47. The use of a laminating film makesit possible for a layer of thermoplastic material, which is used as acover layer, to be joined to the laminating film without the applicationof an additional adhesive.

FIG. 5 shows the structure of a multilayer film 5. The multilayer film 5has a cover layer 51, a transfer film 56 and a mechanically load-bearinglayer 57. The transfer film 56 has a release layer 52, a colored lacquerlayer 53, a metal layer 54 and an adhesive layer 55.

The cover layer 51 comprises a layer of ABS/TPU blend of a thickness of75 μm. The release layer 52 comprises a polyacrylate layer with a layerthickness of about 2 μm. The colored lacquer layer 53 comprises avapor-depositable lacquer and is of a thickness of about 1 μm. The metallayer 54 comprises chromium and is about 10 nm in thickness. Theadhesive layer 55 comprises a pressure-activatable adhesive and involvesa layer thickness of about 2 μm. The mechanically load-bearing layer 57comprises an ABS layer of a thickness of 100 μm, which preferably has ahigh modulus of elasticity.

1. A multilayer film for the construction of skis, in particular forapplication to a ski base body of an alpine ski, water ski, wakeboard,kiteboard, surfboard or snowboard, wherein the multilayer filmcomprises: a multilayer transfer or laminating film of a thickness ofless than 125 μm and comprising two or more thin layers, a mechanicallyload-bearing layer with preferably a high modulus of elasticity isarranged on a surface of the multilayer transfer or laminating film, anda cover layer is arranged on another surface of the multilayer transferor laminating film.
 2. A multilayer film as set forth in claim 1,wherein the transfer or laminating film has an adhesive layer, afunctional layer and a release layer.
 3. A multilayer film as set forthin claim 2, wherein the release layer is a clear lacquer layer whichacts as a bonding layer in relation to the cover layer.
 4. A multilayerfilm as set forth in claim 2, wherein the functional layer has a metallayer.
 5. A multilayer film as set forth in claim 2, wherein thefunctional layer has a thin film layer succession which produces colorshifts by means of interference.
 6. A multilayer film as set forth inclaim 2, wherein the functional layer has a replication layer into whicha diffractive structure or a macrostructure is embossed.
 7. A multilayerfilm as set forth in claim 2, wherein the functional layer has an HRIlayer.
 8. A multilayer film as set forth in claim 2, wherein thefunctional layer has a colored lacquer layer.
 9. A multilayer film asset forth in claim 1, wherein the transfer or laminating film isdeep-drawable.
 10. A multilayer film as set forth in claim 1, whereinthe cover layer and the mechanically load-bearing layer are eachrespectively thicker than the transfer or laminating film, wherein thecover layer is in particular of a thickness of between 50 and 125 μm andthe mechanically load-bearing layer is in particular of a thickness ofbetween 100 m and 2 mm.
 11. A multilayer film as set forth in claim 1,wherein the mechanically load-bearing structure is embossed orstructured.
 12. A multilayer film as set forth in claim 1 wherein themechanically load-bearing layer is transparent.
 13. A multilayer film asset forth in claim 1, wherein the cover layer is transparent.
 14. Amultilayer film as set forth in claim 1, wherein the cover layercomprises a thermoplastic material.
 15. A multilayer film as set forthin claim 1, wherein the cover layer comprises a printing ink or alacquer, in particular a casting lacquer, a dip lacquer or a spraylacquer.
 16. A multilayer film as set forth in claim 1, wherein thecover layer is structured.
 17. A multilayer film as set forth in claim1, wherein additional decoration is printed on to the multilayertransfer or laminating film.
 18. A ski, in particular an alpine ski,water ski, wakeboard, kiteboard, surfboard or snowboard, having a skibase body comprising one or more layers, wherein a multilayer film asset forth in claim 1 is applied to the ski base body on the side of theski in opposite relationship to the sole running surface.
 19. A ski asset forth in claim 18, wherein the mechanically load-bearing layer isjoined to the ski base body.
 20. A ski as set forth in claim 18, whereinthe cover layer is joined to the ski base body.
 21. A process for theproduction of a multilayer film for the construction of skis, inparticular for the production of a multilayer film for application to aski base body of an alpine ski, water ski, wakeboard, kiteboard,surfboard or snowboard, wherein a multilayer transfer or laminating filmof a thickness of less than 125 μm and comprising two or more thinlayers is applied to a surface of a mechanically load-bearing layer witha preferably high modulus of elasticity and a cover layer is applied toa surface of the multilayer transfer or laminating film, which is inopposite relationship to the mechanically load-bearing layer.
 22. Aprocess for the production of a ski, in particular an alpine ski, waterski, wakeboard, kiteboard, surfboard or snowboard, wherein a multilayerfilm as set forth in claim 1 is applied to the ski base body on the sideof the ski, which is in opposite relationship to the sole runningsurface.